A microwave technology has a distinct engineering advantage in an urban area, a remote area, or a special area (such as a river) by directly transmitting data over space without laying an optical fiber, a cable, or the like. According to the microwave technology, networking is easy, a using method is flexible, and it takes little time to activate a service. With the development of the microwave technology, costs of a microwave device gradually decrease. Therefore, the microwave technology is used more and more widely.
The microwave device generally uses different frequencies to simultaneously transmit and receive signals, and a duplexer is used to separate the transmitted and received signals. However, a duplexer is generally large in size and heavy in weight. With the development of the microwave technology, a microwave device develops towards a wide frequency band, miniaturization, and low costs. However, in one aspect, it is difficult to implement miniaturization of a duplexer, and it is even difficult to integrate a duplexer into an integrated circuit chip; and in another aspect, it is difficult for a duplexer to support a wide frequency band due to its structure.